The present invention relates to an endless belt shaped electrophotographic photoconductor comprising an electroconductive support material and a photoconductive layer formed thereon, having a joint portion for combining the opposite end portions thereof in such a manner that the photoconductor is worked into an endless belt form, which joint portion comprises an electroconductive overcoating layer formed on the photoconductive layer, or additionally with a joint reinforcement resin layer inserted between the electroconductive overcoating layer and the photoconductive layer in the joint portion.
Conventionally, as a belt-shaped electrophotographic photoconductor, there is known an endless belt shaped electrophotographic photoconductor which comprises a rectangular support film including an electroconductive layer thereon, and a photoconductive layer formed on the electroconductive layer, with the opposite end portions of the rectangular support film being connected, whereby it is worked into an endless belt shaped photoconductor.
Such a conventional endless belt shaped electrophotographic photoconductor has the shortcomings that the joint portion is cracked or a photoconductive layer portion near the joint portion is cracked or peeled off the support film in the course of repeated use of the photoconductor.
Such belt shaped electrophotographic photoconductor has another shortcoming that complete quenching of the electric charges at the joint portion cannot be carried out once the joint portion has been electrically charged at the charging step. In particular, it is difficult to discharge the joint portion at the cleaning step of cleaning the photoconductor by a quenching lamp after a toner image transfer step, so that toner is deposited on the electrically charged joint portion at the succeeding development step and a substantial amount of the deposited toner has to be removed by the cleaning apparatus in the course of the copying process, since the joint portion is not employed as image formation area, but toner remains on the joint portion. As a result, the toner deposited on the joint portion becomes a heavy load on the cleaning apparatus and causes smearing of the inside of the copying machine. Furthermore, the amount of the toner that must be recovered as waste toner increases due to the electric charging of the joint portion.
In order to eliminate the above shortcomings of the conventional belt shaped electrophotographic photoconductor, a method of forming an electroconductive overcoating layer on the joint portion has been proposed in order to electrically connect the electroconductive layer with the electroconductive layer of the photoconductor. This method is capable of preventing the accumulation of electric charges in the joint portion. However, cracking of the joint portion and the photoconductive layer near the joint portion and peeling of the photoconductive layer off the support material cannot be sufficiently prevented by the conventional electroconductive overcoating layer comprising finely-divided electroconductive particles dispersed in a resin.